Diaphragm



J. M. BARR DIAPHRAGM May 19, 1953 Filed Dec. 12, 1946 INVENTOR join/EBayBY AGE/VT Patented May 19, 953

, DIAPHRAGM John M. Barr, West Hartford, Conn., assignor, by.

mesne assignments, to

Niles -Bement-Pond Company, West "Hartford, Conn., a corporation .ofNewJersey- Application December 12, 1946, Serial No. 715,786

13 Claims. (01.13'7-793) The present invention relates to diaphragms fordifferential pressure responsive mechanisms.

Such diaphragms are commonly formed 'of fabric impregnated with rubberor some rubber like material. The diaphragm usually comprises a flatsheet in which an annular convolution is formed by molding underpressure after the application of uncured rubber to the fabric. Thediaphragm then consists of a flat central portion and a flat annularedge portio'n,'separated by the convolution. In use, the annular edgeportion is usually clamped between two rigid members. Rigid reinforcingdiscs are also placed on the opposite sides of the flat central portion.When the diaphragm is subjected to pressure differences on its oppositesides, the central portion moves with respect to the edge portion. Thismovement is commonly utilized in differential pressure responsivemechanisms for various purposes, for example, to operate a valve orswitch.

Difficulties have been experienced with such diaphragms for severalreasons. One reason is that the forced molding of the convolution in thenormally flat fabric sets up unequal stresses in the threads of thefabric. Such unequal stresses not only occur in the convolution itself,but in the adjacent flat portions which are maintained flat while theconvolution is formed. The natural tendency of such flat portions wouldbe to distort and twist as the convolution is formed. Since the fabricin that portion of the diahpragm is forced to remain flat duringformation of the convolution, stresses are set up in the thread of theflat portions.

Another difficulty that has been encountered with such diaphragms isthat the diaphragm is stressed in shear at the edges of the convolution,where it merges into the flat portion. When a differential pressure isapplied to the diaphragm, it tends to tear the diaphragm at the edge ofthe convolution.

An object of the present invention is to provide an improved pressuredifferential responsive diaphragm.

Another obiectof the invention is to provide a differential pressureresponsive diaphragm in which only the convolution is formed of'flexiblematerial.

A further object is to provide animproved differential pressureresponsive diaphragm in i which the flexible material is stressed onlyin tension and not in shear by the application of differentialpressures.

A further'object is to provide an improved method of constructing adifferential pressure responsive diaphragm. 1

Other objects and advantages of the present invention will becomeapparent from a consideration of the appended specification, claims anddrawing, in which I Figure 1 represents a fragmentary cross-sectionalView of a diaphragm constructed in accordance with the principles of myinvention,

Figures 2, 3, 4, 5 and 6 represent fragmentary cross-sectional views ofmodified forms of diaphragm construction using the principles of myinvention, and

Figure 7 illustrates a, complete diaphragm, such as that shown in Figure5, as utilized in a differential pressure operated valve mechanism.

In Figure 1, the complete diaphragm consists of a rigid outer annularmember l0 and a rigid central disc member 12. These rigid members arejoined by a flexible member M. The flexible member I4 is preferablyformed of fabric impregnated with rubber or rubber-like material. Wherethe term rubber is used hereafter in this specification and claims, itshould be understood that this term is intended to be generic to rubberand all other plastic materials having similar properties.

' The flexible member I4 comprises a convolution l6 of substantiallysemi-circular cross-section and straight-sided tubular portions l8 and20 on opposite sides of the convolution Hi. The edges of the tubularportions l8 and 20 are clamped in U-shaped ring members 22 and 24. Thering members 22 and 24 are molded in the rigid members [0 and I 2, whichare preferably formed of plastic or other suitable moldable material.

In constructing a diaphragm as shown in Figure 1, it is first necessaryto form the flexible member I4. This is preferably done by molding underpressure an annular convolution to which uncured rubber has beenapplied. After the flexible member has been formed as shown in thedrawing, the U-shaped ring members 22 and 24 are clamped to its edges,by placing the edges in the open end of the U and pinching the sidestogether. The assembly consisting of the flexible member l4 and therings 22 and 24 is then placed in a suitable mold, and the rigid membersill and I2 are molded around the ring members 22 and 24. A secure bondis thus formed between the rigid members l0 and I2 and the flexiblemember l4.

It should be noted that the tubular portions l8 and 20 of the flexiblemember l4 are not adjoined by fiat portions, so that the stressesusually set up by molding such members with adjoining fiat portions areavoided. It should also be notedthat the tubular portions IB and 20extend sub stantially at right angles to the rigid members Ill and I2,so that stresses of the flexible member I4 due to the application of adifferential pressure to the diaphragm structure are stresses in tensionand not in shear. The flexible mem-'- ber I does not rest on a corner ofeither of the member 4 may be the same as shown in Figure-I 1. After itis formed, rubber beads are molded on its edges, as shown at 3% and 32.The rubber beads 30 and. 32 are then molded .intothe rigid members Inand I2. The molded rubber beads 30 and 32 take the place of the metalrings 22 and 24 of Figure 1.

There is shown in Figure '3 a modifiedform of diaphragm construction inwhich the flexible member is formed somewhat difierently. The flexiblemember is shown at 40, and has a convolution '42 and straight sidedtubular portions u' andiflt corresponding to the convolution;anditnbular portions 18 and Zil. Figures 1. and 2.- However, instead ofterminating at the endofthe tubular portions, the edges ofthe-flexiblemember n continue-intoedge portions Mend as of in regularformation. These edge portions. 5,9 and Starenot rigidly. held'durins.the p ocess of molding the .flexiblemember, so they can assume whatever"shape is necessary to relieve, their own internal stresses. After theflexible member. is formedit is molded directly into th r gid-mew hersHand 2, the edgeportions 48 and 50 serving as-anchors for the --ilexiblemember. There is shown in .Figure A a modification of the'structilreofFigure 3. In the Figure 1% ar rangememeach of the tubular portions 44and 46 is provided witha pair of reinforcing rings 52 and 54. Thestructure is otherwise the same as in Figured.

Figure illustrates another modifiedformoi diaphragm construction. Herethelflexible member 49 is formed the same as the member-490i Figure 3..However, the edge portions 45 and so are molded into a pair of rubberrings beans 58., respectively. The. ring 55 is-clamped between a pair.of plateswfill and 52' lay-means. ofa rivet .64.. The ring 53 issimilarly clamped between a pair of plates .65 and .68 by means ofarivet l0.

. Figure Sillustrates amodificationjof thesilructure shown in Figure 5.Here the edge portions of the flexible member 411 are molded withinrubber ring members '12 andl' l. The. ring l2 is clamped between a pairof plates 16 and T8, and thering M is clamped between a pair of plates80 and 82. The ring 14 is clamped by means of a bolt 84 and nut 85. Anyequivalent clam-ping mechanism maybe used by means of which considerableclam-ping pressure may-bebrought to bear on the rings 12 and M so as toform a leakproof structure. i H

It should be noted that ineach of themodifications shown, the'tubularportlonsof the flexible member are not adjoined by perfectly 'flatportions, so that the internal stresses set up in the flexible member bythe molding process are avoided. Also; it should be noted. that theflexible member in each case extends at right angles to therigid-member, and that it extends in. each case a substantial portionofits length into the rigid-member, so that the stresses .app1led...tothe flexible member by the application of .a pres-.- sure differentialto the. diaphragm are tension stre esra her than shear stre ses..

...-In:-Figure '7 the diaphragm structure of figure 5 is shown as usedin aprcssure difierential resI Qnsive valve mechanism. The plate members.60 and 62 are clamped betwe n usperand lower castingsilfl andflZ whichtogether format-housing for the valve mechanism. The diaphr gm 4structure separates the housing into two expansible chambers Mandilfit"suitable fluid pressure is communicated to chamber through conduit .98and a greater fluid pressure is communicated to chamber 95 through aconduit I00.

. The stem 102 on the valve Hi l is clamped to the plates 66 and 68 bymeans of a nut I06. The valve 104 en ages a seat formed on the casting9.21 and controls the flow of fluid from chamber 99 through anputletconduit [68. A spring H0 biases the valve I'M to closed position.

. Wheneventhepressure differential between chambers Stand 9S exceeds thevalue determined-by the strength of spring us, the central portion ofthe diaphragm assembly moves up, opening the valve. ,1

The terms and expressions which I have em ployed are used as terms ofdescription and not of limitation, and I have no intention in the use ofsuch terms and expressions, of excluding any equivalent of the featuresshown and described or p r ions th reof, but recognize, ha various.modifications are possible within the scope of the appended ,claims.

I claim as my invention:

1. Adifieren-tial fluidpressure responsive dialpbragm comprising a rigidannular member, a rigid --central disc: member having a diameter smallerthan the inner diameter of saidannular member, a thin flexible annular;element con-- necting said members, said element having a convolutionwith straight, tubular sidewalls terminating, in outwardly extendingfianges,1and means connecting said flanges to said members insubstantially parallel relation thereto, so that said element isstressed only in tensionan'd not in shear by the application of adiflerential fluid pressure to said diaphragm.

2. Adifierentialfiuid pressure responsive dia* phragm comprising a rigidannular member, a rigid disc member concentric with and spaced from saidannular member, an annular element orthin fiexiblematcrial adapted toconnect said members, said element having an annular con- ;Volutionwith. straight tubular side-walls termiating in outwardly flared flangessubstantially at right n les with sidewalls. and .rcunded'ioi fifiattaching said flanges to said members in substantially parallel,relation thereto, so that said element is stressed only in tension andnot in shear at said joints by theapplication of forcesact-ingparallelto said tubular portions. 3. .A ifferential fluidpressure responsive dia phra m comprising a rigid annular member;'arigid disc member concentric with and spaced from said annular member,an annular element 2- thin flexible material adapted to connect saidmembers, said element having an annular convolution with straighttubular, sidewallsterminating in outwardly extending flanges, "and meansconnecting said'flanges'to said' members with said flanges lying withinand fastened to said connecting means, so that said elementis stressedonly in tension by forces acting parallel to said tubular portions.

4. A differential fluid pressure responsive p r em omp i ing a rigidannular membrane rigid disc member concentric with and spaced from saidannular member, an annular element of hin flexible material adaptedto-connect'said members, said element having anannular corn volution andstraight tubular sidewalls with flanges extending outwardlysubstantially at right angles on .oppositesides of said convolution; andresilient means connecting said flanges to said members so that saidelement is stressed only in tension by forces acting on said membersparallel to said tubular portions.

5. A differential fluid pressure responsive diaphragm comprising a rigidannular member, a rigid disc member concentric with and spaced from saidannular member, an annular element of thin flexible material adapted toconnect said members, said element having an annular convolution andstraight tubular sidewalls with flanges extending substantially at rightangles on opposite sides of said convolution, said members having atleast their adjacent edge portions formed of molded material, and havingsaid flanges fastened within said edge portions so that said element isstressed only in tension by forces acting on said members parallel tothe tubular portions of said element.

6. A diiferential fluid pressure responsive diaphragm comprising a rigidannular member, a rigid disc member concentric with and spaced from saidannular member, an annular element of thin flexible material adapted toconnect said members, said element having an annular convolution andstraight tubular sidewalls with flanges extending substantially at rightangles on opposite sides of said convolution, and means clamping saidflanges to said members with uniform pressures so that said flanges areuniformly compressed and said element is stressed only in tension byforces acting on said members parallel to said tubular portions.

7. A diflerential fluid pressure responsive diaphragm comprising a rigidannular member, a rigid disc member concentric with and spaced from saidannular member, an annular element of thin flexible material adapted toconnect said members, said element having an annular convolution andstraight tubular sidewalls terminating in outwardly extending flanges onopposite sides of said convolution, and a pair of rings of moldedmaterial, said rings having said flanges molded therein, and meansclamping said rings to said members so that said portions aresubstantially perpendicular to said members.

8. A difierential fluid pressure responsive diaphragm comprising a rigidannular member, a rigid disc member concentric with and spaced from saidannular member, and a thin flexible annular member adapted to connectsaid rigid members, said flexible member having an annular convolutionand straight tubular sidewalls with flanges extending outwardlysubstantially at right angles on opposite sides of said convolution, anda ring connecting one edge of each of said flanges with one of saidrigid members, said ring being molded integrally with one of itsassociated members and engaging the other of its associated members.

9. A differential fluid pressure responsive diaphragm comprising a rigidannular member, a rigid disc member concentric with and spaced from saidannular member, and a thin flexible annular member adapted to connectsaid rigid members, said flexible member having an annular convolutionand straight tubular sidewalls terminating in outwardly extendingflanges on opposite sides of said convolution, and a ring connectingeach of said flanges with one of said rigid members, said rigid membershaving at least their adjacent edge portions formed of molded materialand having one edge of said ring molded within said edge portion so thatthe tubular portions of said flexible member extend perpendicularly tosaid rigid members.

10. A differential fluid pressure responsive diaphragm comprising arigid annular member, a rigid disc member concentric with and spacedfrom said annular member, and a thin flexible annular member adapted toconnect said rigid members, said flexible member having an annularconvolution and straight tubular sidewalls with flanges extendingoutwardly substantially at right angles on opposite sides of saidconvolution, at least the adjacent edge portions of said rigid membersbeing formed of molded material and having a part of the tubular and allof said flange portions of said flexible member fastened within saidadjacent edge portions so that the tubular portions of said flexiblemember extend perpendicularly to said rigid members.

11. A differential fluid pressure responsive diaphragm comprising arigid annular member, a rigid disc member concentric with and spacedfrom said annular member, an annular element of thin flexible materialadapted to connect said members, said element having an annularconvolution and straight tubular sidewalls terminating in outwardlyflared flanges parallel to said rigid members, on opposite sides of saidconvolution, and a pair of rings of molded material, each of said ringshaving a substantial length of said tubular portion, all of said flangeportions of said element molded therein, and means for fastening saidrings to said members so that said portions are substantiallyperpendicular to said members.

12. A differential fluid pressure responsive diaphragm comprising arigid annular member, a rigid disc member concentric with and spacedfrom said annular member, an annular element of thin flexible materialadapted to connect said members, said element having an annularconvolution with straight tubular sidewalls terminating in outwardlycurved flanges on opposite sides of said convolution, and a pair ofcontoured rings clampingly engaging a part of said sidewalls, saidmembers having at least their adjacent edge portions formed of moldablematerial, and having a pair of said rings and said flanges molded withinsaid edge portions so that said element is stressed only in tension byforces acting on said members parallel to the tubular portions of saidelement.

13. A differential fluid pressure responsive diaphragm comprising arigid annular member, a rigid disc member concentric with and spacedfrom said annular member, and a thin flexible annular member adapted toconnect said rigid members, said flexible member having an annularconvolution with straight tubular sidewalls terminating in outwardlycurved flanges on opposite sides of said convolution, and two pairs ofreinforcing rings, one pair lying on either side of a part of saidsidewalls, said rigid members having at least their adjacent edgeportions formed of moldable material, and having said flanges with apart of said reinforcing rings molded directly within said adjacent edgeportions so that the tubular portions of said flexible member extendperpendicularly to said rigid members.

JOHN M. BARR.

References Cited in the flle Of this patent UNITED STATES PATENTS NumberName Date 2,218,090 Marinsky Oct. 15, 1940 2,272,327 Sauzedde Feb. 10,1942 2,275,712 Zand Mar. 10, 1942 2,330,797 Bohannan Oct. 5, 1943

